Dina Abdulmajid

Rice (Oryza sativa L.) has an impressive range of phenotypic and genetic diversity, making it an important crop for global food security. Since rice phenotypic and genetic diversity are essential for enhancing the sustainability of rice production, an understanding of these variations is crucial for breeding efforts. Numerous factors, such as plant height, panicle number, grain properties, etc., exhibit phenotypic diversity in rice. Moreover, genetic diversity is essential for breeding and enhancing rice in multiple manners. This research investigates the phenotypic diversity of thirteen promising lines relative to their parents. Since the genetic effect reflects the plant’s phenotype, forty SSR markers were used to investigate the genotypic diversity. Generally, six promising genotypes produced much better grain yields than their parents. Across two years, the number of filled grains panicle⁻¹ and the number of unfilled grains panicle⁻¹ had the highest phenotypic and genotypic coefficients of variability percentage. The challenges towards novel variety with distinct characteristics were met in several promising lines under examination, which showed a significant and positive association between the grain yield and the number of panicles per plant, the number of filled grains per panicle, and the 1000-grain weight. Furthermore, five SSR markers were discovered to be polymorphic during the genetic diversity investigation, and the genotypes were classified into five clusters based on SSR marker data. The findings, together with further details, can be used to release novel and unique varieties.

Key message A novel quantitative trait locus qIGL1, which performed a positive function in regulating grain length in rice, was cloned by the map-based cloning approach; further studies revealed that it corresponded to LOC_Os03g30530, and the IGL1 appeared to contribute to lengthening and widening of the cells on the surface of grain hulls. Abstract Grain length is a prominent determinant for grain weight and appearance quality of rice. In this study, we conducted quantitative trait locus mapping to determine a genomic interval responsible for a long-grain phenotype observed in a japonica cultivar HD385. This led to the identification of a novel QTL for grain length on chromosome 3, named qIGL1 (for Increased Grain Length 1); the HD385 (Handao 385)-derived allele showed enhancement effects on grain length, and such an allele as well as NIP (Nipponbare)-derived allele was designated qigl1 ^HD385 and qIGL1^NIP, respectively. Genetic analysis revealed that the qigl1^HD385 allele displayed semidominant effects on grain length. Fine mapping further narrowed down the qIGL1 to an ~ 70.8-kb region containing 9 open reading frames (ORFs). A comprehensive analysis indicated that LOC_Os03g30530, which corresponded to ORF6 and carried base substitutions and deletions in HD385 relative to NIP, thereby causing changes or losses of amino-acid residues, was the true gene for qIGL1. Comparison of grain traits between a pair of near-isogenic lines (NILs), termed NIL-igl1^HD385 and NIL-IGL1^NIP, discovered that introduction of the igl1^HD385 into the NIP background significantly resulted in the elevations of grain length and 1000-grain weight. Closer inspection of grain surfaces revealed that the cell length and width in the longitudinal direction were significantly longer and greater, respectively, in NIL-igl1^HD385 line compared with in NIL-IGL1^NIP line. Hence, our studies identified a new semidominant natural allele contributing to the increase of grain length and further shed light on the regulatory mechanisms of grain length.

Background Quinclorac- main herbicide targeting to barnyard grass, has been used for decades in rice fields. Echinochloa species have been reported evolving into quinclorac resistance.Objective: Quinclorac resistance and its mechanism remain undisclosed in Echinochloa oryzoides (Ard.) Fritsch that needs to be uncovered. Methods Dose-response assays were performed, followed by ethylene synthesis, and related enzyme activities along with gene transcription were studied. β-CAS activity and its molecular docking were investigated. Results E. oryzoides evolved into 21 times resistance to quinclorac [...] Abstract Background Quinclorac- main herbicide targeting to barnyard grass, has been used for decades in rice fields. Echinochloa species have been reported evolving into quinclorac resistance.Objective: Quinclorac resistance and its mechanism remain undisclosed in Echinochloa oryzoides (Ard.) Fritsch that needs to be uncovered. Methods Dose-response assays were performed, followed by ethylene synthesis, and related enzyme activities along with gene transcription were studied. β-CAS activity and its molecular docking were investigated. Results E. oryzoides evolved into 21 times resistance to quinclorac

High sensitivity of rice coleoptile elongation length to exogenous gibberellin is a beneficial trait to utilize superior rice cultivars that could not be used originally under water direct-seeded conditions. In the present study, we mined favorable alleles for the trait by combining the phenotypic data of 358 rice accessions with their genotype data of 262 simple sequence repeat (SSR) markers via genome wide association mapping method. Totally, 17 SSR marker loci significantly associated with gibberellin sensitivity index (GSI) of coleoptile elongation length under 10 cm depth of water, were detected by general linear model and mixed linear model across two years, with percent phenotypic variation explained larger than 10%. Twenty nine favorable alleles for GSI on the 17 loci were discovered with phenotypic effect value (PEV) larger than 0.1 cm/cm and RM6869-110 bp showed the largest PEV (0.27 cm/cm). Based on PEV of marker-alleles having positive effects on GSI, seven parental combinations were predicted to improve GSI. In addition, 7 loci for GSI were co-located with loci associated with coleoptile elongation length per se, and one locus (RM1182 on chromosome 5) was co-located with that associated with coleoptile elongation length after gibberellin-soaked seed, under germination condition of 10 cm depth of water. These favorable allele(s) could be used to improve two target traits simultaneously.